The present invention relates to photochromic naphthopyran compounds. More particularly, this invention provides photochromic bis-naphthopyran compounds as well as methods for their manufacture and their use.
Several types of photochromic compounds are known for use in applications in which reversible color change, or darkening, induced by sunlight is desirable. These applications include for example, ophthalmic lenses, solar protection lenses, filters, camera optical systems, decorative objects, windows and the like.
However, the known compounds are disadvantageous in that they do not exhibit both high optical density and the ability to return to their original color quickly once the activating light source is removed. Thus, there is a need for new compounds with fast response to ultraviolet (xe2x80x9cUVxe2x80x9d) irradiation, high colorability and long lifetime.
The present invention provides bis-naphthopyran compounds that exhibit a wide range of color, i.e., from pink to purple to blue gray, upon activation by a source of UV light and that, when the irradiation is discontinued, the original color is recovered. The bis-naphthopyran compounds of the present invention exhibit broad coloration ability, fast coloration response, and good fatigue-resistance.
In one embodiment, the present invention provides a compound comprising: 
wherein X is sulfur or oxygen;
Rxe2x80x2, Rxe2x80x3 may be the same or different and are each independently hydrogen, hydroxy, halogen, nitro, cyano, allyl, linear or branched (C1-C20)alkyl, (C3-C20)cycloalkyl, (C1-C20)alkoxy, (C1-C20)alkylacetylenyl, phenylacetylenyl, (C1-C20)alkenyl, phenylvinyl, halo(C1-C20)alkyl, halo(C3-C20)cycloalkyl, halo(C1-C20)alkoxy, aryl, aryloxy or heteroaryl optionally substituted with (C1-C6)alkyl or (C1-C6)alkoxy; arylalkyl or heteroarylalkyl; nitrogen-containing heterocyclic ring having 5 or 6 atoms optionally substituted with (C1-C6)alkyl or (C1-C6)alkoxy, xe2x80x94N(R1)R2, CON(R1)R2, wherein R1 and R2 may be the same or different and are each independently hydrogen, (C1-C20)alkyl, (C3-C20)cycloalkyl, and optionally substituted phenyl; xe2x80x94OCOR, xe2x80x94COOR or xe2x80x94COR, wherein R represents hydrogen, (C1-C20)alkyl, (C3-C20)cycloalkyl, or aryl or heteroaryl optionally substituted with (C1-C6)alkyl or (C1-C6)alkoxy;
Axe2x80x2, Axe2x80x3 may be same or different and are each independently:
(a) linear or branched (C1-C12)alkyl, (C3-C12)cycloalkyl, aryl(C1-C6)alkyl or heteroaryl(C1-C6)alkyl, (C1-C6)alkoxy(C1-C6)alkyl, (C1-C12)alkoxy, halo(C1-C12)alkyl, (C1-C12)haloalkoxy, (C1-C12)alkylthio;
(b) substituted or unsubstituted aryl groups;
(c) substituted or unsubstituted heteroaryl groups;
(d) a group of the following formulae: 
wherein B is hydrogen, (C1-C12)alkyl or substituted or unsubstituted aryl;
(e) unsubstituted or mono-substituted pyrazolyl, pyridyl, imidazolyl, pyrazolinyl, imidazolinyl, or acridinyl, each of the said substituents being (C1-C6)alkyl, (C1-C6)alkoxy, fluoro, chloro, or phenyl.
(f) a group of the following formulae: 
xe2x80x83wherein C and D may be the same or different and are each independently carbon, oxygen, (C1-C12)alkyl nitrogen, or (C1-C12)acyl nitrogen;
xe2x80x83R3 and R4 are each hydrogen or (C1-C12)alkyl; and
xe2x80x83wherein the phenyl moiety is optionally substituted with (C1-C12)alkyl, (C1-C12)alkoxy, (C2-C12)acyl, fluoro, or chloro;
n is an integer from 1 to 8; and
m is an integer from 0 to 3.
xe2x80x9cNitrogen-containing heterocyclic ring having 5 or 6 atomsxe2x80x9d includes, without limitation, pyrrolidino, piperidino, morpholino, and the like. xe2x80x9cHalogenxe2x80x9d or xe2x80x9chaloxe2x80x9d means fluoro, chloro, bromo, or iodo. Preferably fluoro, chloro, or bromo is used. xe2x80x9cArylxe2x80x9d includes, without limitation, phenyl or naphthyl. xe2x80x9cHeteroarylxe2x80x9d includes, without limitation, furyl, thienyl, pyrryl, indolyl, benzofuryl, benzothienyl, pyridyl, dibenzofuryl, dibenzothienyl, and carbazolyl.
xe2x80x9cSubstituted aryl or heteroaryl groupsxe2x80x9d includes, without limitation aryl or heteroaryl groups that are mono-, di-, or tri-substituted by a substituent that is: halogen nitro, amino, cyano, hydroxy, epoxy, vinyl, allyl, hydroxyethoxy, methoxyethoxy, hydroxyethoxyethoxy, methoxyethoxyethoxy; (C1-C12)alkyl, (C1-C12)alkoxy, (C1-C12)alkylaryl, aryl, aryloxy, aryl(C1-C12)alkyl, aryl(C1-C12)alkoxy, (C1-C12)alkoxyaryl, halo(C1-C12)alkyl, haloaryl, cyclo(C3-C12)alkyl, cyclo(C1-C12)alkoxy, aryloxyaryl, aryloxy(C1-C12)alkyl, aryloxy(C1-C12)alkoxy, acryloxy, methacryloxy; a heterocyclic nitrogen-containing substituent, such as N-(C1-C12)alkylpiperazino, N-aryl-piperizino, aziridino, indolino, pyrrolidino, pyrrolino, piperidino, (C1-C4)alkylpiperidino, di(C1-C4)alkylpiperidino, 4-piperidinopiperidino, morpholino, 2,6-di(C1-C4)alkylmorpholino, thiomorpholino, thioazolidino, tetrahydroquinolino, pyrryl; xe2x80x94N(R1)R2, CON(R1)R2, wherein R1 and R2 are the same or different and are independently hydrogen, (C1-C12)alkyl, (C3-C12)cycloalkyl, phenyl, mono- or di-substituted phenyl; or xe2x80x94COR, xe2x80x94OCOR or xe2x80x94COOR, wherein R is hydrogen, (C1-C12)alkyl, (C3-C12)cycloalkyl, halo(C1-C6)alkyl, unsubstituted, mono- or di-substituted phenyl, unsubstituted, mono- or di-substituted naphthyl, unsubstituted, mono- or di- substituted furyl, or thienyl, and combination thereof.
In a preferred embodiment, the present invention provides a compound of Formula I wherein:
X is sulfur or oxygen;
Rxe2x80x2, Rxe2x80x3 are the same or different and are each independently hydrogen, nitro, cyano, allyl, fluoro, chloro, bromo, trifluoromethyl, trichloromethyl, pyrrolidino, piperidino, morpholino, phenyl, benzyl; linear or branched (C1-C6)alkyl, (C1-C6)alkoxy, or xe2x80x94OCOR or xe2x80x94COOR wherein R is hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl;
Axe2x80x2, Axe2x80x3 are the same or different and are each independently:
(a) linear or branched (C1-C6)alkyl, (C3-C6)cycloalkyl, aryl(C1-C4)alkyl or heteroaryl(C1-C4)alkyl, (C1-C6)alkoxy(C1-C6)alkyl;
(b) unsubstituted, mono-, di-substituted aryl selected from phenyl or naphthyl, preferably substituted in the meta position, the para position, or both;
(c) unsubstituted or mono-substituted heteroaryl groups that are furyl, thienyl, pyrryl, indolyl, benzofuryl, benzothienyl, pyridyl, dibenzofuryl, dibenzothienyl, or carbazolyl the substituents being nitro, amino, cyano, hydroxy, epoxy, hydroxyethoxy, methoxyethoxy, hydroxyethoxyethoxy, methoxyethoxyethoxy, fluoro, chloro, bromo, iodo, vinyl, allyl, trifluoromethyl, phenyl, (C1-C6)alkyl, (C1-C6)alkoxy, cyclo(C3-C6)alkyl, cyclo(C1-C6)alkoxy, (C1-C6))alkylamino, di(C1-C6)alkylamino, diarylamino, phenylacetylenyl, or phenylvinyl;
a heterocyclic nitrogen-containing substituent, such as N(C1-C6)alkylpiperazino, N-aryl-piperizino, aziridino, indolino, pyrrolidino, pyrrolino, piperidino, (C1-C4)alkylpiperidino, di(C1-C4)alkylpiperidino, 4-piperidinopiperidino, morpholino, 2,6-di(C1-C4)alkylmorpholino, thiomorpholino, thioazolidino, tetrahydroquinolino, or pyrryl;
N(R1)R2, CON(R1)R2, wherein R1 and R2 are the same or different and are each independently hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, phenyl or xe2x80x94COR, xe2x80x94OCOR or xe2x80x94COOR wherein R is hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, or phenyl;
n is an integer from 1 to 6; and
m is an integer from 0 to 2.
In a still more preferred embodiment, the invention provides a compound of Formula I wherein:
X is sulfur;
Rxe2x80x2, Rxe2x80x3 are the same or different and are each independently hydrogen, nitro, cyano, fluoro, chloro, bromo, pyrrolidino, piperidino, morpholino, phenyl, benzyl, (C1-C4)alkyl, or (C1-C4)alkoxy;
Axe2x80x2, Axe2x80x3 are the same or different and are each independently:
a linear or branched (C1-C4)alkyl, (C3-C6)cycloalkyl;
unsubstituted, mono-, or di-substituted phenyl, preferably substituted in the meta position, para position or both with the substituents being one or more of nitro, amino, acyl, cyano, methoxy, ethoxy, methoxyethoxy, fluoro, chloro, vinyl, allyl, methoxycarbonyl, ethoxycarbonyl, (C1-C4)alkyl, di(C1-C4)alkylamino, piperazino, piperidino, arylperidino, morpholino, pyrrolidino, aziridino, acryloxy, methacryloxy, phenylacetylenyl, phenylvinyl;
unsubstituted, mono-substituted heteroaromatic groups, such as furyl, thienyl, pyrryl, substituted with a substituent that is (C1-C4)alkyl or phenyl;
n is an integer from 1 to 4, and
m is, independently, integer from 0 to 2.
In a yet more preferred embodiment, the compound of the invention is:
5,5xe2x80x2-Bis[3-(p-methoxyphenyl)-[3H]-naphtho[2,1-b]pyran-3-yl]-2,2xe2x80x2-bithiophene;
5,5xe2x80x2-Bis[3-(p-methylphenyl)-[3H]-naphtho[2,1-b]pyran-3-yl]-2,2xe2x80x2-bithiophene;
5,5xe2x80x2-Bis[3-(p-fluorophenyl)-[3H]-naphtho[2,1-b]pyran-3-yl]-2,2xe2x80x2-bithiophene;
5,5xe2x80x2-Bis[3-(o-fluorophenyl)-[3H]-naphtho[2,1-b]pyran-3-yl]-2,2xe2x80x2-bithiophene;
5,5xe2x80x2xe2x80x3-Bis[3-(p-methoxyphenyl)-[3H]-naphtho[2,1-b]pyran-3-yl]-[2,2xe2x80x2,5xe2x80x2,2xe2x80x3,5xe2x80x3,2xe2x80x2xe2x80x3[-quaterthiophene;
5,5xe2x80x2xe2x80x3-Bis[3-(naphthalene-2-yl)-[3H]-naphtho[2,1-b]pyran-3-yl]-[2,2xe2x80x2,5xe2x80x2,2xe2x80x3,5xe2x80x3,2xe2x80x2xe2x80x3[-quaterthiophene; or
5,5xe2x80x2xe2x80x3-Bis[3-(o-fluorophenyl)-[3H]-naphtho[2,1-b]pyran-3-yl]-[2,2xe2x80x2,5xe2x80x2,2xe2x80x3,5xe2x80x3,2xe2x80x2xe2x80x3[-quaterthiophene.
The compounds of Formula I may be prepared by the process illustrated in Reactions A through D below or, alternatively, in a process illustrated in Reaction E. In Reaction A, the corresponding aromatic ketone is formed from an acid chloride and the reaction may be the following Friedel-Crafts reaction:
Reaction A: 
The acid chloride represented by Formula II and heterocyclic compound represented by Formula III are dissolved in dichloromethane and reacted in the presence of a Lewis acid, such as stannous chloride, to form the corresponding substituted aromatic ketone represented by Formula IV. The substituents A, Rxe2x80x3, X and n are the same as defined hereinabove. The Friedel-Crafts reaction, and the conditions for carrying it out, are described in Olah, George A., 3 xe2x80x9cFriedel-Crafts and Related Reactions,xe2x80x9d Interscience Publishers (1964).
In Reaction B, the heteroaromatic ketone of Formula IV is reacted with sodium acetylide in a suitable solvent, such as anhydrous tetrahydrofuran (xe2x80x9cTHFxe2x80x9d), dimethylsulfoxide (xe2x80x9cDMSOxe2x80x9d) or the like, to form the corresponding propargyl alcohol represented by graphic formulae V.
Reaction B: 
The reaction may be conducted at room temperature in a 1 to 100 mmol scale.
In Reaction C, the propargyl alcohol of Formula V may be coupled with a naphthol represented by Formula VI in the presence of a catalytic amount of acid, such as pyridinium p-toluenesulfonate (xe2x80x9cPPTSxe2x80x9d), to generate naphthopyran represented by graphic formulae VII. This reaction and the conditions for carrying it out are described in Helv Chim. Acta, 81 (7), 1293 (1998).
Reaction C: 
Alternatively and preferably, Reaction C may be carried out using 3 xc3x85 molecular sieves. This reaction may be performed in the presence of a non-polar solvent, preferably benzene, toluene, xylene, chloroform, 1,1-dichlorethane, 1,2-dichloroethane, carbon tetrachloride, or a combination thereof. More preferably, the reaction is performed in toluene or 1,2-dichloroethane. The reaction temperatures may be from about 50 to about 160xc2x0 C., preferably about 80 to about 140xc2x0 C., more preferably about 90 to 120xc2x0 C. Reaction time may be about 1 hour to about 3 days, preferably about 2 hours to about 2 days, and more preferably about 2 hours to about 24 hours. The preferred ratio of reactants is 1.1:1:0.5 to about 1:1.1:0.05 (V:VI:PPTS).
In Reaction D, the naphthopyran of Formula VII is treated with butyl lithium and then cupric chloride in a suitable solvent, such as anhydrous THF, and generate the homo-coupled product represented by Formula I.
Reaction D: 
The reaction may be carried out at between about xe2x88x9278xc2x0 C. and ambient temperatures for about 5 to about 48 hours. The reactants preferably are used in a ratio of about 1:1.1:1.1 to about 1:1.5:2 (VII:BuLi:CuCl2).
Alternatively, the bis-naphthopyran compound of the invention may be prepared in as shown in Reaction E. In Reaction E, a bis-heteroaromatic ketone of Formula IX may be generated by Friedel-Crafts reaction of a heterocyclic compound of Formula III. Upon treatment with sodium acetylide, the desired bis-propargyl alcohol of Formulae IV may be generated. Coupling of the bis-propargyl alcohol of Formula X with naphthol of Formulae VI in the presence of a catalytic amount of an acid such as pyridinium p-toluenesulfonate (xe2x80x9cPPTSxe2x80x9d), generates the desired bis-naphthopyran compound.
Reaction E: 
The bisnaphthopyran compounds of the invention may be used alone or as a mixture with other compounds of Formula I. Additionally, the compounds of the invention mat be used in a mixture with other types of known photochromic compounds including, without limitation, naphthopyran, spirooxazine, mixtures with one or more nonphotochromic dyes, or combinations thereof. In addition one or more stabilizers, such as an antioxidant, one or more UV absorbent such as 2-hydroxyphenylbenzotriazoles or 2-hydrpxyphenyltriazones, one or more anti radical agents such as 5-ethoxybenzoimidazole, or combinations thereof maybe added to these mixtures to improve photochromic properties.
One particular advantage of the compounds of the present invention is that the absorption spectra of the colored form of the activated bisnaphthopyran compounds of Formula I typically exhibit higher optical densities or absorbances, and longer lifetime, than the corresponding photochromic naphthopyrans of Formula VII. In solution, the compounds of the invention are pale pink or yellow. When activated by a source of UV radiation, such as solar radiation or light from a mercury or xenon lamp, solutions of the bis-naphthopyran compounds of the invention rapidly develop an intense coloration, depending on the structure of compound, ranging from pink to purple to blue gray. The response of bis-naphthopyran of Formula I to UV irradiation is much faster than that of naphthopyran represented by graphic formulae VII shown in Reaction C.
A wide variety of fading ranging from 3 seconds to 300 seconds depending on the structure of bis-naphthopyran compounds is also provided. When the fade is slow, or longer than 100 seconds, the bis-naphthopyran compounds of Formula I exhibit high colorability due to the fully opening of the two photochromic functionalities in the bis-naphthopyran. To obtain a slow fading compound, a fluoro substituent is placed in the ortho position of the 3-phenyl group. Slow fading is desirable for certain uses including, without limitation, windows.
When the fade is fast, or less than 60 seconds, the bis-naphthopyran compound of the invention provide higher optical density and longer life-time than the corresponding photochromic naphthopyrans represented by Formulae VII. Fast fading is obtained without substitution at the ortho position and, optionally, by placing a substituent at the para postion of the 3-phenyl group. Suitable substituents include, without limitation, fluoro, methoxy, methyl, ethyl, phenyl, piperidino, or morpholino. Fast fading is useful in a wide variety of setting including, without limitation, in spectacle lenses.
The bis-naphthopyran compounds of the invention alone, mixtures thereof, or mixtures of these with other types of known photochromic compounds may be introduced into a composition that can be applied to or introduced into a host material. The compositions may include inks or coating compositions. The photochromic bis-naphthopyran compounds may be present in an organic solvent or an organic polymer host.
If a solvent is used, the solvent may be any solvent capable of dissolving the photochromic substances. Suitable solvents include, without limitation, benzene, toluene, methyl ethylketone, acetone, ethanol, methanol, propanol, isopropanol, tetrahydrofuran, dioxane, ethyl acetate, ethylene glycol, xylene, cylcohexane, N-methyl pyrrolidinone, and the like, and mixtures thereof. When dissolved in chloroform, the compounds of the invention have a much larger molar extinction coefficient (xcex5) and, thus, can block more UV radiation, than the corresponding naphthopyran precursor represented by Formula VII.
The host materials used with the compounds of the invention may be any materials for which exhibition of photochromic characteristics is desirable. Typically, the host material will be an organic material and preferably is a transparent or optically clear organic material. Such materials including, without limitation, a polymer, a copolymer, or mixtures thereof. Suitable host materials include, without limitation: poly(ally carbonate), polyepoxy, polyacrylates, polyethylene, polypropylene, polyvinyl chloride, polymethacrylates, poly (C1-C12)alkyl methacrylates, polyoxyalkylene methacrylates, cellulose acetate, cellulose triacetate, cellulose acetate butyrate, acetyl cellulose, poly (vinyl acetate), poly (vinyl alcohol), polyurethanes, polythiourethane, polysiloxane, polyamide, polystyrene, and copolymers including, without limitation, acrylates, methacrylates, methyl methacrylates, ethylene glycol bis methacrylate, vinyl acetate, vinyl butyral, urethane, thiourethane, diethylene glycol bis(ally carbonate), diethylene glycol dimethacrylate, diisopropenyl benzene, and the like and combinations thereof.
Typically, the compounds of the invention are incorporated into the host material by any convenient means, including, without limitation, dissolution, dispersion, polymerization with other components of the host material, incorporation into a coating applied to one surface of the organic host material, or combinations thereof. Alternatively, the compounds may be imbibed into the surface of the host material. Further more, the compounds may be coated onto the host material using various means such as spray coating, spin coating, spread coating, curtain coating, casing or dip coating.
The bis-naphthopyran compounds of the invention and mixtures thereof may be used in those applications in which organic photochromic substances are typically employed, such as optical lenses, and plano lenses, face shields, goggles, camera lenses, windows, automotive transparencies, inks, e.g., a liquid or paste containing photochromic dyes used for writing and printing, decorative objects such as plastic films and sheets, textiles, and coating compositions, e.g., paints, and verification marks on security documents, e.g., documents such as passports, driver""s licenses, banknotes, and the like. Coating compositions are defined herein to include polymeric coating compositions prepared from materials such as polymethacrylate, polyurethane, polyepoxy resin and other resin used to produce synthetic polymers.
The amount of the bis-naphthopyran compound of the present invention used depends on the desired degree of darkening, provided that it is perceptible to the naked eye upon activation. Moreover, the particular amount used depends often upon the method used to incorporate or apply a photochromic substance. Typically, the more photochromic substance applied or incorporated, the greater is the color intensity up to a certain limit. In particular, it is used in a quantity of about 0.001 to about 20 weight percent based on the total weight of the object to be article.
The present invention is illustrated by the following examples, which are in no way intended to limit the scope of the present invention. Numerous modifications and variations will be apparent to those skilled in the art.